[lisper]

> I decided to use colors rather than numbers or letters to identify each basic set, though I didn't use the same colors Newton did; mine are equidistant in the hue circle.

"Lawn green" and "medium spring green" look completely identical to me. Maybe I have a really obscure kind of color blindness?

[jessriedel]

I have normal vision. I wouldn't say completely identical when they are side-by-side, but they are very close. It's effectively impossible to discriminate them when they are not side-by-side, which for this plot is very important.

The author's mistake was this: "[my colors] are equidistant in the hue circle". The problem is that the hue circle (at least under the parameterization scheme he used) is not uniform over discrimination, i.e., the ability to discriminate two hues is not invariant under displacing them an equal amount along the circle. (I presume this is one of those situation where it's misleading to think about three primary colors on equal footing because of quirks of human vision biology.)

First, the author could have chosen 7 hues at max-saturation that were easier to discriminate than this. But more importantly, he should have used the other color axes: saturation and brightness. dark red (~maroon) and light red (~pink) are a lot easier to discriminate, even when not next to each other, than the two shades of green he used.

[bobsmooth]

Those colors are similar but obviously distinct to me. Maybe your monitor is the issue?

[lisper]

I thought of that. I'm on a Macbook Air and initially I had Night Shift on but even after I disabled it I still couldn't tell the difference.

[bobsmooth]

Maybe you should take a few color blindness tests.